Openverse is a search engine for open content such as images, photographs and audio. Openverse is now owned by the WordPress Foundation. With Openverse you can search Creative Commons licensed and public domain content from over 45 different media sources, including Wikimedia Commons, Europeana, Flickr, Freesound, Jamendo etc. plus a good number of musea, mainly in the USA, such as Smithsonian or the Metropolitan. Openverse is the successor of CC Search, which was developed within Creative Commons. At present it gives access to well over 600 million items.
Free on https://wordpress.org/openverse/ for browser.